This research is directed toward identifying certain areas in the brain in which the neurons are especially sensitive to the acute and chronic effects of narcotics, particularly morphine. The underlying methodological approach in the study is the use of multiple-unit impulse recording, with drug effect monitored simultaneously in many different brain areas. Once key sites are located, further studies will help determine whether a given area is being affected directly by the drug or whether the effect is secondary to some influences elsewhere in the central nervous system or in the periphery. Finally, further research will focus on the key brain areas, and will test a variety of hypotheses about biochemical mechanisms of morphine action, using multiple-unit recording as an assay system.